The present invention relates to heart valve prostheses. In particular, the present invention relates to aortic heart valve prostheses with an efficient and easy to use fastening system for implantation of the prosthesis.
Prostheses, i.e., prosthetic devices, are used to repair or replace damaged or diseased organs, tissues and other structures in humans and animals. Prostheses must be generally biocompatible since they are typically implanted for extended periods of time. For example, prostheses can include artificial hearts, artificial heart valves, ligament repair material, vessel repair, surgical patches constructed of mammalian tissue and the like.
Prostheses can be constructed from natural materials such as tissue, synthetic materials or a combination thereof. For example, prostheses formed from purely synthetic materials, such as mechanical heart valve prosthesis, can be manufactured from, for example, biocompatible metals, ceramics, carbon materials, such as graphite, polymers, such as, polyester, and combinations thereof. Heart valve prostheses can be formed with rigid occluders or leaflets that pivot to open and close the valve, or with flexible leaflets that flex to open and close the valve.
Although mechanical heart valves with rigid pivoting occluders or leaflets have the advantage of proven durability through decades of use, they are associated with blood clotting on or around the prosthetic valve. Blood clotting can lead to acute or subacute closure of the valve or associated blood vessel. For this reason, patients with implanted mechanical heart valves remain on anticoagulants for as long as the valve remains implanted. Anticoagulants impart a 3-5% annual risk of significant bleeding and cannot be taken safely by certain individuals.
Besides mechanical heart valves, heart valve prostheses can be constructed with flexible tissue leaflets or polymer leaflets. Prosthetic tissue heart valves can be derived from, for example, porcine heart valves or manufactured from other biological material, such as bovine pericardium. Biological materials in prosthetic heart valves generally have profile and surface characteristics that provide laminar, nonturbulent blood flow. Therefore, intravascular clotting is less likely to occur than with mechanical heart valve prostheses.
In the heart, blood flow between the atria and the ventricles and out of the ventricles is controlled by heart valves. Blood flow from the right ventricle of the heart passes into the pulmonary artery. Blood flow from the left ventricle of the heart passes into the aorta. Aortic heart valves are located between the left ventricle and the aorta where the aorta connects with the heart. Similarly, pulmonary valves are located between the right ventricle and the pulmonary artery.
The native aortic heart valve has three leaflets that open to allow flow into the aorta and close to prevent back flow into the left ventricle. Tissue leaflets have sufficient flexibility to open and close. This allows for placement of a prosthetic valve within the aorta at or near the opening into the heart. Each of the three leaflets of a natural valve is attached to the wall of the aorta along a nonplanar curve.
Attachment of the stentless aortic valve prosthesis is complicated since suturing must be performed on both the inflow and outflow edges of the prosthesis to secure the prosthesis. Significant pressures are exerted against the valve in use. Thus, it is desirable to suture the prosthetic valve along the commissure supports to ensure that the valve does not pull away from the aorta or pulmonary artery. That suturing along the commissures is difficult because the valve is within the aorta. Thus, attachment of the valve is further complicated since suturing must be performed on both the inflow and outflow edges of the valve to secure the valve.